• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 1998.06a
• /
• pp.432-437
• /
• 1998

Power systems have uncertain dynamics due to a variety of effects such as lightning, severe storms and equipment failures. The variation of the effective reactance of a transmission line due to a fault is an example of uncertainty in power system dynamics. Hence, a robust controller to cope with these uncertainties is needed. Recently fuzzy controllers have become quite popular for robust control due to its capability of dealing with unstructured uncertainty. Thus in this paper we design an adaptive fuzzy controller using an input-output linearization approach for the transient stabilization and voltage regulation of a power system under a sudden fault. Simulation results show that satisfactory performance is achieved by the proposed controller.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.11a
• /
• pp.213-213
• /
• 2009

In this paper, we investigated the current limiting characteristics due to the application location of the superconducting fault current limiter (SFCL) such as the feeder, the bus, the secondary side of transformer in a power distribution system. In addition, the quench and the recovery characteristics of the SFCL installed in each location of the power distribution system were compared each other. Through the analysis, in case that the SFCL was applied into the feeder line, its current limiting and voltage-drop compensating characteristics were confirmed to be the more effective. On the other hand, the power burden of the SFCL was increased higher compared to the SFCL'S other application location.

• Proceedings of the KIEE Conference
• /
• 1991.07a
• /
• pp.354-357
• /
• 1991

In the case of system operation, a line overload cause damage to spread an whole range of power system. Of the theorems on load shedding, this study applied power distribution theorem and load reduction theorem which are local load shedding method, which are not affected by the magnitude of the power system and need not a large memory capacity and computation time. In this paper, we treat the problem of overload when power system occurred to fatal fault. Especially, there is the special case that local load shedding theorem is not always solved. Therefore, we introduce a solved device of the problem and construct the expert system of expanded local load shedding. Because proposed method uses the merits of expert system, in the case of system operation, the system operator don't embarrass to fatal fault and promptly deals with.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.527-528
• /
• 2011

송전선로에서 발생하는 고장의 대부분은 낙뢰에 의한 상-대지간 섬락이나 외물접촉, 혹은 애자련의 오손에 의한 절연파괴 등이 대부분이다. 그리고 대분의 고장은 큰 고장전류를 흘리게 되어 보호계전기가 동작하여 고장구간을 신속하게 분리하게 된다. 그러나, 본 고장사례는 매우 희귀한 고장 사례로서, 고저항 아크 지락에 의하여 발생하는 과도회복전압(TRV: Transient Recovery Voltage)이 애자련에 섬락을 일으킨 경우이다. 본 연구에서는 EMTP (Electro-Magnetic Transient Program)를 이용하여 고저항 지락시 아크의 단속에 의하여 과도회복전압이 발생할 가능성이 있음을 보였으며, 고장기록장치(Fault Recorder)에 나타난 파형 기록과의 유사성을 확인하였다. 또한, 고저항 지락에 의하여 직류분이 초기에 방전됨으로써 고장전류 파형에 직류분 오프셋이 나타나지 않게 됨을 밝혔다.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.25 no.3
• /
• pp.273-286
• /
• 2017

We develop an inspection method for bearing faults with a rapid change in the rotation speed and present indexes for the pass/fail inspection. At the end of line, impulse noises generated by the operation of machines and conveyors may distort the inspection results. In this paper, we present robust inspection indexes for bearing faults under impulse noises, by taking into account fault signals having pulse train. Using logistic regression, we optimize the pass/fail criterion for each index and evaluate the performance of the inspection indexes based on the total error rate.

• Proceedings of the KIEE Conference
• /
• 2008.10a
• /
• pp.149-150
• /
• 2008

본 논문에서는 운전중인 154 kV 및 345 kV 송전선로에서 철탑 구조의 변경 없이 애자의 수량을 증결하여 절연성능을 보강하는 방안에 대한 연구결과를 제시하고 있다. 송전선로에서 발생 가능한 상용주파과전압과 개폐과 전압의 최대값을 EMTP 해석모델을 이용하여 계산하고 이로부터 뇌섬락 고장확률과 급속오손고장확률을 고려한 절연거리 증대 및 소요애자수량 방법을 제시하고 있다.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.4
• /
• pp.1376-1385
• /
• 2017

This paper proposes a method for estimating the expected frequency of voltage swells caused by asymmetrical faults in a power system. Although voltage swell is less common than voltage sag, repeated swells can have severe destructive impact on sensitive equipment. It is essential to understand system performance related to voltage swells for finding optimal countermeasures. An expected swell frequency at a sensitive load terminal can be estimated based on the concept of an area of vulnerability (AOV) and long-term system fault data. This paper describes an effective method for calculating an AOV to voltage swells. Interval estimation for an expected swell frequency is also presented for effective understanding of system performance. The proposed method provides long-term performance evaluation of the frequency and degree of voltage swell occurrences.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2007.05a
• /
• pp.274-279
• /
• 2007

The fault identification of electrical rotating machinery have been special interests due to one of important elements in the industrial production line. It is directly related with products quality and production costs. The sudden breakdown of a motor will affect to the shut down of the whole processes. Therefore, rotating machines are required to a periodic diagnosis and maintenance for improving its reliability and increasing their lifetime. The objective of this work is to develop the diagnosis system with current signals for the effective identification of healthy and faulty motors using the developed diagnosis algorithm, which consists of the feature calculation, feature extraction, and feature classification procedures.

• Proceedings of the KIEE Conference
• /
• 2001.07b
• /
• pp.717-719
• /
• 2001

This paper deals with simulation of the three-phase dc reactor type fault current limiter(FCL). This is a preliminary step to develop the FCL's faculties for an application to high voltage transmission line. A three-phase dc reactor type FCL consists of transformers, diodes, and a superconducting coil. By this simulation for the short-circuit test we can investigate the safety of FCL's elements. And, result of simulation will contribute parameter toward optimal design.

• Proceedings of the KIEE Conference
• /
• 2000.07a
• /
• pp.425-427
• /
• 2000

The purpose of this study is to find the cause of the damage to the GCB(Gas Circuit Breaker), since the GCB of the 154kV power plant at the Hap-Cheon Dam has already been damaged twice. We researched the characteristics of this class of circuit breaker and the possible causes for this type of damage to the GCB using the FTA(Fault Tree Analysis) Method. We studied the optimal maintenance method of the GCB, the stability analysis and power serge protection of Hap-Cheon Dam, and the power serge and fault list of the power transmission line to help prevent a reoccurrence of the problem.